Smoke detector



FIG. 1 is a perspective view showing the underside and left side, together with the adjacent peripheral surfaces of my new design;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is an underside plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a rear elevational view thereof; and,

FIG. 7 is a right side elevational view thereof. 

The ornamental design for a smoke detector, as shown and described. 